“It is clear the events we have seen over the past few days in Boston were an attempt to kill American citizens and terrorize a major American city,” the lawmakers asserted in the statement. “The accused perpetrators of these acts were not common criminals attempting to profit from a criminal enterprise, but terrorists trying to injure, maim, and kill innocent Americans.”

The Obama administration, however, has maintained that terrorism suspects arrested inside the United States should be handled exclusively in the civilian criminal justice system, the Times notes.

And Sen. Carl Levin, D-Michigan, chairman of the Senate Armed Services Committee, issued his own statement saying that the laws of war don’t apply to Tsarnaev.

“I am not aware of any evidence so far that the Boston suspect is part of any organized group, let alone al-Qaida, the Taliban, or one of their affiliates–the only organizations whose members are subject to detention under the Authorization for Use of Military Force, as it has been consistently interpreted by all three branches of our government,” Levin noted. “In the absence of such evidence I know of no legal basis for his detention as an enemy combatant.”

Levin asserted that to hold the Tsarnaev as an enemy combatant “would be contrary to our laws and may even jeopardize our efforts to prosecute him for his crimes.”

An enemy combatant designation would allow military authorities to question Tsarnaev at length without a lawyer. The Obama administration has already indicated it would use a public-safety exception to Miranda for early questioning. The Associated Press has reported that the federal public defender’s office in Massachusetts will seek to represent the 19-year-old suspect once he is charged.

Sen. Graham told the Times that if indeed no evidence emerged that Tsarnaev is linked to al-Qaida, then he shouldn’t be held as an enemy combatant. But in the early stages of the investigation, Graham argued that the designation should be made while such links are explored.

“You can’t hold every person who commits a terrorist attack as an enemy combatant, I agree with that,” Graham told the Times. “But you have a right, with his radical Islamist ties and the fact that Chechens are all over the world fighting with Al Qaeda–I think you have a reasonable belief to go down that road, and it would be a big mistake not to go down that road. If we didn’t hold him for intelligence-gathering purposes, that would be unconscionable.”

The Supreme Court has upheld the indefinite military detention of an American citizen, Yaser Esam Hamdi, captured on a foreign battlefield. But federal appeals courts have disagreed on whether it’s lawful to hold an American captured on U.S. soil without a trial, such as Jose Padilla. Padilla was transferred to civilian courts before the Supreme Court resolved the circuit court conflict.